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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef BASE_WIN_SCOPED_HANDLE_H_
#define BASE_WIN_SCOPED_HANDLE_H_
#include <windows.h>
#include "base/base_export.h"
#include "base/basictypes.h"
#include "base/location.h"
#include "base/logging.h"
#include "base/move.h"
namespace base {
namespace win {
// TODO(rvargas): remove this with the rest of the verifier.
#if defined(COMPILER_MSVC)
// MSDN says to #include <intrin.h>, but that breaks the VS2005 build.
extern "C" {
void* _ReturnAddress();
}
#define BASE_WIN_GET_CALLER _ReturnAddress()
#elif defined(COMPILER_GCC)
#define BASE_WIN_GET_CALLER __builtin_extract_return_addr(\\
__builtin_return_address(0))
#endif
// Generic wrapper for raw handles that takes care of closing handles
// automatically. The class interface follows the style of
// the ScopedStdioHandle class with a few additions:
// - IsValid() method can tolerate multiple invalid handle values such as NULL
// and INVALID_HANDLE_VALUE (-1) for Win32 handles.
// - Receive() method allows to receive a handle value from a function that
// takes a raw handle pointer only.
template <class Traits, class Verifier>
class GenericScopedHandle {
MOVE_ONLY_TYPE_FOR_CPP_03(GenericScopedHandle, RValue)
public:
typedef typename Traits::Handle Handle;
// Helper object to contain the effect of Receive() to the function that needs
// a pointer, and allow proper tracking of the handle.
class Receiver {
public:
explicit Receiver(GenericScopedHandle* owner)
: handle_(Traits::NullHandle()),
owner_(owner) {}
~Receiver() { owner_->Set(handle_); }
operator Handle*() { return &handle_; }
private:
Handle handle_;
GenericScopedHandle* owner_;
};
GenericScopedHandle() : handle_(Traits::NullHandle()) {}
explicit GenericScopedHandle(Handle handle) : handle_(Traits::NullHandle()) {
Set(handle);
}
// Move constructor for C++03 move emulation of this type.
GenericScopedHandle(RValue other) : handle_(Traits::NullHandle()) {
Set(other.object->Take());
}
~GenericScopedHandle() {
Close();
}
bool IsValid() const {
return Traits::IsHandleValid(handle_);
}
// Move operator= for C++03 move emulation of this type.
GenericScopedHandle& operator=(RValue other) {
if (this != other.object) {
Set(other.object->Take());
}
return *this;
}
void Set(Handle handle) {
if (handle_ != handle) {
Close();
if (Traits::IsHandleValid(handle)) {
handle_ = handle;
Verifier::StartTracking(handle, this, BASE_WIN_GET_CALLER,
tracked_objects::GetProgramCounter());
}
}
}
Handle Get() const {
return handle_;
}
operator Handle() const {
return handle_;
}
// This method is intended to be used with functions that require a pointer to
// a destination handle, like so:
// void CreateRequiredHandle(Handle* out_handle);
// ScopedHandle a;
// CreateRequiredHandle(a.Receive());
Receiver Receive() {
DCHECK(!Traits::IsHandleValid(handle_)) << "Handle must be NULL";
return Receiver(this);
}
// Transfers ownership away from this object.
Handle Take() {
Handle temp = handle_;
handle_ = Traits::NullHandle();
if (Traits::IsHandleValid(temp)) {
Verifier::StopTracking(temp, this, BASE_WIN_GET_CALLER,
tracked_objects::GetProgramCounter());
}
return temp;
}
// Explicitly closes the owned handle.
void Close() {
if (Traits::IsHandleValid(handle_)) {
Verifier::StopTracking(handle_, this, BASE_WIN_GET_CALLER,
tracked_objects::GetProgramCounter());
if (!Traits::CloseHandle(handle_))
CHECK(false);
handle_ = Traits::NullHandle();
}
}
private:
Handle handle_;
};
#undef BASE_WIN_GET_CALLER
// The traits class for Win32 handles that can be closed via CloseHandle() API.
class HandleTraits {
public:
typedef HANDLE Handle;
// Closes the handle.
static bool CloseHandle(HANDLE handle) {
return ::CloseHandle(handle) != FALSE;
}
// Returns true if the handle value is valid.
static bool IsHandleValid(HANDLE handle) {
return handle != NULL && handle != INVALID_HANDLE_VALUE;
}
// Returns NULL handle value.
static HANDLE NullHandle() {
return NULL;
}
private:
DISALLOW_IMPLICIT_CONSTRUCTORS(HandleTraits);
};
// Do-nothing verifier.
class DummyVerifierTraits {
public:
typedef HANDLE Handle;
static void StartTracking(HANDLE handle, const void* owner,
const void* pc1, const void* pc2) {}
static void StopTracking(HANDLE handle, const void* owner,
const void* pc1, const void* pc2) {}
private:
DISALLOW_IMPLICIT_CONSTRUCTORS(DummyVerifierTraits);
};
// Performs actual run-time tracking.
class BASE_EXPORT VerifierTraits {
public:
typedef HANDLE Handle;
static void StartTracking(HANDLE handle, const void* owner,
const void* pc1, const void* pc2);
static void StopTracking(HANDLE handle, const void* owner,
const void* pc1, const void* pc2);
private:
DISALLOW_IMPLICIT_CONSTRUCTORS(VerifierTraits);
};
typedef GenericScopedHandle<HandleTraits, DummyVerifierTraits> ScopedHandle;
} // namespace win
} // namespace base
#endif // BASE_SCOPED_HANDLE_WIN_H_
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